With the popularity of electrophoretic paint, electrophoretic painting lines have erected poles, but in many electrophoresis paint equipment supply, technical professional, experienced suppliers often have a higher cost, just entered the industry of equipment manufacturers to intervene at a low price, because not professional enough, often in many details of the design defects, electrophoresis line equipment process determines the quality of the paint film, if the congenital shortage is difficult to make up for in the future, so it must be paid attention to.
The main circulation system is mainly composed of pumps, valves, filters, pipes, nozzles, etc. In order to keep the tank liquid uniform to prevent precipitation, the electrophoresis tank must be equipped with a main circulation system and the pump should be 24h non-stop operation, if the fault stops immediately need to be repaired, the stop time should not exceed 2h, to prevent the tank sedimentation caused by pipeline blockage and poor coating. The flow direction of the electrophoresis tank is consistent with the direction in which the workpiece is running. The flow rate of the electrophoresis liquid is generally 2 to 4 times the running speed of the workpiece; the flow rate of the liquid level is not less than 0.2m/s; the flow rate of the bottom of the tank is not less than 0.4m/s; the liquid flow rate of the circulating pipeline should be maintained at more than 0.4m/s, so as to prevent the solids of the electrophoresis liquid from settling in the pipeline, which has strict requirements for the selection of the size and quantity of the circulating pump.
Types of circulating pumps
In the electrophoresis tank circulation system, horizontal or vertical centrifugal pumps are generally used. Split horizontal requirements The use of double mechanical sealing requires the addition of liquid sealing equipment. Usually use clean ultrafiltration liquid or deionized water seal, the pressure is 3 ~ 5kgf / cm, the rotation speed of the pump is 1450-1470r / min is appropriate. Vertical pumps are usually installed on the auxiliary tank, and the pump suction port should be extended to no less than 1.5 times the diameter of the pipe from the bottom of the tank to minimize eddy currents and to maximize the evacuation of the tank liquid when cleaning the tank. All pumps should be equipped with protective devices to prevent damage to the impeller and pump housing with impurities and particles. Vertical pumps are equipped with a double-layer removable steel mesh mounted on the pump head (suction port) and coated with an insulating coating.
Why not use a high speed circulation pump?
(1) The high speed will cause the local temperature of the tank liquid in the pump to be too high, the long-term operation will lead to the easy aging of the coating resin, the different chemical components in the resin will be separated and precipitated, the tank liquid voltage will be reduced, the paint film will be abnormal, the foaming or shrinking holes will occur, and the physical and chemical properties of the paint film will be significantly reduced.
(2) The high shear force of the rotational speed becomes larger, and the high shear force is easy to cause the demulsification of the paint latex particles, the inorganic pigment packing components are peeled off and precipitated from the organic resin components, the long-term running tank is prone to precipitation, and the paint film is prone to particles.